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44                            Warping of Wood.

wood and, as a consequence, the centre plank is narrower at the
edges while the side planks become drawn in, in the manner
shewn at A. If the tree be cut into quarters, each quarter will
contract, according to the above law, in the manner sketched at
Fig. 55, the sector piece at B becoming narrower, the square at
c becoming rhomboidal, and the circle at D elliptical Even after

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timber has been thoroughly dried, it will always warp If a

shaving be taken off it, as may be seen at Fig. 56, for a

surface is exposed, which, drying, must contract the

has been planed.    It is, therefore, suggested by some authorities

that, in first beginning a pattern, the wood should be

out and.cut to the size required, so as to have some little

to set before being used.    (See Appendix //., /. 787.)

Tools and appliances.—It would be unnecessary in a
like the present to occupy the student with elaborate
of the hand tools used by the pattern maker.    The following
trated list will serve to explain them :